Don't put Cargo into the rustc workspace

This causes problems when first cloning and bootstrapping the repository
unfortunately, so let's ensure that Cargo sticks around in its own workspace.
Because Cargo is a submodule it's not available by default on the inital clone
of the rust-lang/rust repository. Normally it's the responsibility of the
rustbuild to take care of this, but unfortunately to build rustbuild itself we
need to resolve the workspace conflicts.

To deal with this we'll just have to ensure that all submodules are in their own
workspace, which sort of makes sense anyway as updates to dependencies as
bugfixes to Cargo should go to rust-lang/cargo instead of rust-lang/rust. In any
case this commit removes Cargo from the global workspace which should resolve
the issues that we've been seeing.

To actually perform this the `cargo` submodule has been moved to the top
directory to ensure it's outside the scope of `src/Cargo.toml` as a workspace.

4 files changed, 28 insertions, 8 deletions

diff --git a/src/bootstrap/compile.rs b/src/bootstrap/compile.rs
index 46d8d4b4aab..3459c1d2b84 100644
--- a/src/bootstrap/compile.rs
+++ b/src/bootstrap/compile.rs
@@ -417,7 +417,10 @@ pub fn tool(build: &Build, stage: u32, target: &str, tool: &str) {
     // build.clear_if_dirty(&out_dir, &libstd_stamp(build, stage, &host, target));
 
     let mut cargo = build.cargo(&compiler, Mode::Tool, target, "build");
-    let dir = build.src.join("src/tools").join(tool);
+    let mut dir = build.src.join(tool);
+    if !dir.exists() {
+        dir = build.src.join("src/tools").join(tool);
+    }
     cargo.arg("--manifest-path").arg(dir.join("Cargo.toml"));
 
     // We don't want to build tools dynamically as they'll be running across
diff --git a/src/bootstrap/dist.rs b/src/bootstrap/dist.rs
index 67e4dad83ce..5c547f7af5f 100644
--- a/src/bootstrap/dist.rs
+++ b/src/bootstrap/dist.rs
@@ -392,6 +392,7 @@ pub fn rust_src(build: &Build) {
     let src_dirs = [
         "man",
         "src",
+        "cargo",
     ];
 
     let filter_fn = move |path: &Path| {
@@ -535,9 +536,9 @@ pub fn cargo(build: &Build, stage: u32, target: &str) {
 
     let src = build.src.join("src/tools/cargo");
     let etc = src.join("src/etc");
-    let release_num = &build.crates["cargo"].version;
-    let name = format!("cargo-{}", build.package_vers(release_num));
-    let version = build.cargo_info.version(build, release_num);
+    let release_num = build.cargo_release_num();
+    let name = format!("cargo-{}", build.package_vers(&release_num));
+    let version = build.cargo_info.version(build, &release_num);
 
     let tmp = tmpdir(build);
     let image = tmp.join("cargo-image");
@@ -594,7 +595,7 @@ pub fn extended(build: &Build, stage: u32, target: &str) {
     println!("Dist extended stage{} ({})", stage, target);
 
     let dist = distdir(build);
-    let cargo_vers = &build.crates["cargo"].version;
+    let cargo_vers = build.cargo_release_num();
     let rustc_installer = dist.join(format!("{}-{}.tar.gz",
                                             pkgname(build, "rustc"),
                                             target));
@@ -943,7 +944,7 @@ pub fn hash_and_sign(build: &Build) {
     cmd.arg(distdir(build));
     cmd.arg(today.trim());
     cmd.arg(build.rust_package_vers());
-    cmd.arg(build.cargo_info.version(build, &build.crates["cargo"].version));
+    cmd.arg(build.cargo_info.version(build, &build.cargo_release_num()));
     cmd.arg(addr);
 
     t!(fs::create_dir_all(distdir(build)));
diff --git a/src/bootstrap/lib.rs b/src/bootstrap/lib.rs
index 071d0b0b090..4831b380837 100644
--- a/src/bootstrap/lib.rs
+++ b/src/bootstrap/lib.rs
@@ -76,11 +76,12 @@ extern crate num_cpus;
 extern crate rustc_serialize;
 extern crate toml;
 
-use std::collections::HashMap;
 use std::cmp;
+use std::collections::HashMap;
 use std::env;
 use std::ffi::OsString;
 use std::fs::{self, File};
+use std::io::Read;
 use std::path::{Component, PathBuf, Path};
 use std::process::Command;
 
@@ -995,6 +996,21 @@ impl Build {
         self.rust_info.version(self, channel::CFG_RELEASE_NUM)
     }
 
+    /// Returns the `a.b.c` version that Cargo is at.
+    fn cargo_release_num(&self) -> String {
+        let mut toml = String::new();
+        t!(t!(File::open(self.src.join("cargo/Cargo.toml"))).read_to_string(&mut toml));
+        for line in toml.lines() {
+            let prefix = "version = \"";
+            let suffix = "\"";
+            if line.starts_with(prefix) && line.ends_with(suffix) {
+                return line[prefix.len()..line.len() - suffix.len()].to_string()
+            }
+        }
+
+        panic!("failed to find version in cargo's Cargo.toml")
+    }
+
     /// Returns whether unstable features should be enabled for the compiler
     /// we're building.
     fn unstable_features(&self) -> bool {
diff --git a/src/bootstrap/step.rs b/src/bootstrap/step.rs
index a5c0d11d219..a11726a57db 100644
--- a/src/bootstrap/step.rs
+++ b/src/bootstrap/step.rs
@@ -559,7 +559,7 @@ pub fn build_rules<'a>(build: &'a Build) -> Rules {
     rules.build("tool-qemu-test-client", "src/tools/qemu-test-client")
          .dep(|s| s.name("libstd"))
          .run(move |s| compile::tool(build, s.stage, s.target, "qemu-test-client"));
-    rules.build("tool-cargo", "src/tools/cargo")
+    rules.build("tool-cargo", "cargo")
          .dep(|s| s.name("libstd"))
          .dep(|s| s.stage(0).host(s.target).name("openssl"))
          .dep(move |s| {